Emmison test

I have just taken an emmision test on an upg egige 2000mod without CAT…

800 rpm
CO - 1,197%
CO2 - 7,16%
HC - 1202 ppm
O2 - 10,02 %
Lambda 1,506

Does this looks normal when u dont have the CAT fitted???.. The guy who made the test said smt like it could look like the engine is not burning the fuel proparbly… ???

Im a bit worried abou the hig HC… Is it correct it should been around 200-300 ppm even if u have cat fitted or not…And the lambda is a calculated nummber, and this could mean its to much oxygen in the mixture??? or what???.. Just got this information in generally disccusion about cars, And since im really close to buy this car, it would been nice to sort this probl out:)

I’m no expert, but it would appear your idle speed is to low, it should be between 1150 and 1350rpm for a normal idle test. At this speed you should have a max CO reading of 0.5%. I’m not sure but I think that if you had a cat fitted it would reduce your C0 reading by 1%, giving 0.197% which is OK, the HC for this speed should no more than 200 ppm. The next test would be to carry out a fast idle check, this should be done at 2500 to 3000rpm where you should get the following results
Min Lamba 0.95
HC Max 200
CO max 0.3
Max Lamba 1.09

My advice would be to get them to refit the cat and do the emissions test again at the correct speeed.
Hope this helps.


Uff im a bit confusied about the HC… ??
As I said I been told the HC dosent change that much if u got a CAT or not… But after searching a bit more here… im not sure anymore… Maybe all my values was OK?? Uff ufff… I dont know

hmmm… maybe ure right… tnks 4 information:) I was also thining about the rpm… And yes I will fit a CAT and do the test over again… hopefully on monday

But how is it with the idle speed… is this the same rpm for every brand of car. or?? its just a bit weird we do the test differently in nrw and GB


also make sure the engine and exhaust are well up to temperature before the test is run, don’t let them cool while you wait.

Well… I read smt here in a previous post… And I like what I read, I guess the ppl who told me the ppm should been around 2-300 ppm wven without cat was wrong:)

here is what I read:

The difference between ‘Cat-on’ and ‘Cat-off’ figures is amazing (ask me if you’re interested - I have printouts for both tests but e.g. HC drops from 2213ppm to 19ppm with the cat fitted! )

Simmular to my problem…now I can relax before doiing the test over again:)

Jusr recived a mail from lotus regarding emmison:)

The Exige is designed to meet the emission regulations in standard 177ps
form when fitted with a catalytic converter. The figures you quote are not
relevant if obtained without a cat. The converter will reduce the HC, it is
only CO2 which is not affected by the cat. The 190 upgrade is for track use
only, and is not intended for road going vehicles. The normal idle speed
for the Exige is 1250 rpm.

Just got 1 last question for u guys… when u say idle speed… is this the speed when u start up the engine and u dont touch the gas pedal?? I guess not…Because when I do this I have 800 rpm… and I guess its the wasy its suppose to be…Just had to ask becaus we do the mot test with 800 rpm(speed without touching the pedal)

that’s right, idle speed is the RPM without touching the throttle.

So with the car in netural and not touching the pedals the idle should be 1250rpm with the standard ECU but can be dropped with an aftermarket ECU to something like 800rpm…

When at 800rpm is it very lumpy and bumpy and isn’t a steady 800, sort of jumps between 700 and 1100?


what do u mean with aftermarket ECU.???.Do u mean a 190 version ECU??.. Hmm… Im pretty sure mine is steady at 800 rpm…??? Ill take another check to see if its steady…And if it is steady at 800 rpm is this kind of normal for 190 version… smth i should do smt about?? or?

I guess you need to adjust the base idle speed. Adjustment is made by the screw on the throttle bodies close to where the throttle cable is attached. AFAIK the ecu doesn’t directly control the idle, other than via the IAC valve during the warm-up phase.

Not too sure about the Lotus ECU but the Emerald ECU (aftermarket ECU) you can change the target idle on the ECU software…

I’m just trying to make sure you have a VHPD K series in the back there, the idle should be high and basically sound like a bag of nail in a rusty barrel…

Like it’s going to stall and then pick up again etc. If it’s just purring at 800rpm then that doesn’t seem right to me… But others will comment I’m sure.

Are any exigers near the dealer to check this out?

Well there are no Exigers to check this out…since this is the only one in Norway… I guess its a VHPD K engine, but dont know for sure …its only written smt like Elise on the cam cover (which is normall I guess), cant see any other information on the engine… And the owner knows a lot less about the car compare to me (and I know almost nothing) so I cant ask him
I havent check the ECU but Im pretty sure its Emerald.

Anyway ill make another check when the CAT arrives (hopfully tommorow)


If you’ve got an Emerald ECU, that’s a real bonus Idle speed with an Emerald ECU will probably be around 800rpm, but with the Lotus ECU (either 177 or 190) idle speed will be around 1200rpm - but as Mark says, it will be uneven & vary between 1000 & 1300 rpm.

Keep us posted


if its a standard (or 190) ecu then the idle should be 1250rpm… if its at 800rpm then maybe the Idle Air Control Valve (IACV) needs cleaned out… can be seen by peering down the back of the engine (hang over the rear spoiler to do this) under the airbox, and will have blue silicon pipework leading into it. It can be removed from beneath the car. If it idles steadily at 800rpm i’d have thought it would also need Jenvey throttle bodies as well as a programmable ecu (like Emerald)? has anyone ever seen a standard (or 190) idle reliably this low ?

What else makes you think its got an Emerald?

If the fueling and ignition timing isn’t properly sorted at 800rpm then you will have (possibly insurmountable) difficulty with emmisions… which is one of the reasons the std idle is 1250rpm i think. ?

Lots of usefull information here guys…thanks:)

The reason I belive it could be Emerald, is a bit hard to explain, but I have tryed to dig up the history of this car, and from what I been told, I just thought it might be the Emerald, especially after this 800 rpm… but again im not sure… But I will look for the Emerald sticker on the ECU next time (tommorow maybe)

Hey niceguy, check out my Emerald installation page, so you can see how the Lotus one looks and how different the Emerald is.


I didn’t think it was actually possible to get a smooth idle at 800rpm with the stanrd VHPD cams and timing, just a nature of the beast so to speak… There wouldn’t be any way of mapping them at all to be silky smooth

here is what I read:

The difference between ‘Cat-on’ and ‘Cat-off’ figures is amazing (ask me if you’re interested - I have printouts for both tests but e.g. HC drops from 2213ppm to 19ppm with the cat fitted! )

Simmular to my problem…now I can relax before doiing the test over again:)

It was me - I said that last year having tried to bluff my car through an Mot without the Cat. This year I was smart enough to fit the car a couple of weeks before the test and the figures were even lower - CO2 was nil, HC was 5ppm and lambda 1.03. The cat really does its job …but it makes it too quiet and stifles the upper midrange …so it’s coming off again.


I just been to check to ECU, I just used the inspection hatch. And it looks like the standard ECU:(… Since the car was inside I dident test the idle speed again…I will do as soon as the **** CAT arrives… Hmmm…its a bit weird… But I will take another emmison test with the CAT fitted, and if the idle speed is 800 rpm steady and the values from the emmison test is OK, then it should be Ok… I guess… ??And then Ill buy the car Or should I investigate this more before buying it?? Im sure there is a logic explination for this…

Also starting to wonder if it has the 190 upgrade… For me it dosent sound like its that easy to check… Maybe I should test this???

“On the std one, there is no point on revving past 7200rpm, on the 190 it will still make good power until about 7800rpm and the limiter will kick in at 8000”

But when will the limiter kick in on the std version 7500 rpm? And will it still kick in if u test this with gear in free?? And what happend when the limiter kick in… Its just stable at that rpm …or other ways to tell??

But I also spoke to some ppl who drove this car, and they told me u will fell a reall kick from about 7000 (or was it 7500) rpm, I havent test this due to bad weather:( (and a bit worried to ruin the car before buying it …heh )… But if this is true about this kick…it must be promising…right… because you want fell it on the std version?? or???

Well…that was my noob questions…heh…

It’s a very good sign that the kick is that high up :grin where it should be!

A standard K will run out of guts at about 6000rpm, maybe lower… Sounds like the 800rpm idle is something else and could be nothing to worry about